Gas-lift valve



Patented Apr. 1, 1941 GAS-LIFT VALVE James B. Worthington and George R. -McGee, Oklahoma City, Okla., assignors to Thomas Bryan, Fort Worth, Tex.

Application February 3, 1940, Serial No. 317,088

2 Claims.

This invention relates to gas-lift valves for lifting fluid from wells.

The general object of the invention is to provide an improved gas lift valve of the variable continuous flow type, operating on both fluid differential and velocity control principle.

Another object is to provide a gas-lift valve of the character stated which closes in either direction to shut ofi flow of gas therethrough, closing in one direction by the pressure effect of the gas, and closing in the other direction by a. spring tension alone or in connection with the internal pressure of liquid or other pressure such as the pressure created by the friction flow of well fluid internally of a well tubing.

Another object is to provide a gas-lift valve with the conventional gas inlet but with a multitude of gas outlets employed in an unusual manner whereby such outlets not only provide a distributing means for the gas exhausting from the valve in a manner to more fully realize and use the maximum benefit from said gas, but used further to control the closing differential of the valve while at the same time using a spring of constant tension.

Another object is to provide a gas-lift valve which may be set to operate under a predetermined opening and closing pressure within a minimum range within which any valve will operate without adjustment, so that the valve, when constructed and set for particular size tubing will operate in any well using tubing of such size, regardless of whether the liquid to be lifted is oil, water or a mixture of the two, and regardless of the depth of the well, 50 long as sufiicient pressure is available to lift the liquid from the well or to carry on a flow operation of the liquid from the bottom of the well after the well has been unloaded. 1

Other objects and advantages of the invention will appear hereafter.

With the above and other objects in view, the invention consists in the novel and useful provision, formation, construction, association and relative arrangements of parts, members and features, all as shown in certain embodiments in the accompanying drawing, described generally, and more particularly pointed out in the claims.

In the drawing:

Figure 1 is a vertical longitudinal section of a well equipped with a gas-lift apparatus including a plurality of gas-lift valves embodying this invention for lifting the liquid from the well.

Figure 2 is an enlarged vertical longitudinal section of a portion of the eduction tubing showing one of the couplings in said tubing and one of the gas-lift valves mounted in said coupling.

Figure 3 is an enlarged vertical longitudinal section of the valve herein described, shown in open position, or neutral position.

Figure 4 is a horizontal section taken on line 55 of Figure 3.

Referring more particularly to the drawing, in which corresponding parts are designated by the same reference characters in all of the figures, l designates the valve in its entirety, which includes generally a cylindrical housing 2, a sleeve 3, valve seats 4 and 5 formed on either side of said sleeve 3, a valve stem 6, slidably mounted in said sleeve with clearance therearound, valve closing members I and 8 on said valve stem for seating on seats 4 and 5 in opposite directions, a valve spring 9 and an adjustable valve spring mounting It at one end of the said valve housing, interiorly thereof. The sleeve 3 is fitted in the said housing 2 with one side against an internal flange H in said housing 2 and its other side engaged by one end of a sleeve l2 fitted in said housing, and held in place by a screwed plug 13 in one end of the said housing. As an alternate sleeve 3 may be split and therefore made in two equal halves and thus fitted around the stem 6 and the entire unit press fitted into the housing 2 to the desired position intermediate the interior ends of said housing, and thus dispense with the sleeve l2. The plug I3 is provided with an internal bore I4 extending upwardly therein from its lower end, forming a guide for one end of stem 6. In the opposite end of the valve housing 2, is a spring retainer plug l 0 adjustably threaded into housing 2 by external threads 15 and internal threads in said housing l6.

- Plug Ill may be either locked into fixed position in housing 2 by a lock nut (not shown) or pin or in any other suitable manner retaining said plug in position to maintain the desired tension on spring 9. The interior of said plug Ill is a counterbored forming a spring receptacle lllA and has the additional function of acting as a guide for the end of stem 6. The lower exterior end wall I! of the plug I0 is provided with a screw driver slot I B to receive a screw driver for turning said plug so that the tension on the spring 9 interiorly thereof may be adjusted, thereby controlling to some extent the operating pressure of the valve.

Interiorly one end of the housing 2, is a compartment l9, formed by the plug l3 on one side and the sleeve 3 on the other, comprising an inlet gas chamber. The valve element 8 operates 5A. Said air nipple 22 is hollow bored affording passage of air or gas internally said valve housing 2, and on one end a shoulder 23 is machined affording a stop or spacer controlling the position of the valve I within the coupling5A. Said shoulder 23 fits against the internal side of the valve compartment 23 of the casting 5A; a port 24 thru said side walls of the casting or coupling the sleeve 3 thereby controlling the movement of the stem 6. If the greater number of outlet ports 26 approach the capacity of the area around the stem 6 in the sleeve 3, then the valve stem 6 will not travel to its extreme lower position for the reason the gas has escaped through said ports. If, however, the greater number of ports are as 21 the velocity sweep of the gas past the larger element 1 forces the .stem 6 and the valve element 8 into contact with the seat 5 closing ofi passage of gas through the sleeve 3. Under this operation the greater travel of the stem causes compression of the spring and thus a lower closing pressure'than obtained with the greater numor 5A affords a means of projecting the end of the air nipple -22 from the interior of said coupling 5A to the exterior thereof.

. Interiorly the valve housing 2, and surrounding the stem 6 through sleeve 3, is agas passage area affording communication from the inlet gas compartment I9 to the opposite end of the valve housing 2 and into an outlet gas compartment 25 formed interiorly the housing 2 between the sleeve 3 and the spring retainer I 0. In this compartment 25, the valve element 1 operates. Thus the sleeve 3 controls the movement or travel of the two valve elements 1 and 8 and affords stoppage means for the passage of gas thru said sleeve around stem 6 extending therethrough. Corn municating with the exterior of the housing 2 from this compartment 25, a multitude of small ports 26--21 are drilled thru the exterior walls of housing 2 affording gas outlet passages. Ex teriorly the housing 2 the ports 26 and 21 communicate with the interior of the coupling 5A thus aiiording passage of gas from the valve l to the interior of the coupling 5A and thence into the tubing 28, completing the gas passage cycle from the casing 29 of the well, through the valve I and into the tubing 28.

It will be noted that ports 26 are located in the housing 2, adjacent the outlet side of sleeve 3 and that ports 21 are located at a distance from said sleeve closer to the end of the housing 2 near the spring retainer II). By controlling the number of holes drilled at each point, the passage of gas from the interior of the housing 2 can be controlled to exhaust thru the first holes or 26 thus permitting the valve element 1 to remain in close relationship to the sleeve 3, whereas if the'majority of the ports are as 21 further towards the end of the valve housing 2, the sweep of the gas will force the valve element 1 to near its extreme travel, whereby valve element 8 will now approach the opposite end of the s'leeve 3 and be forced onto its seat 5 of the sleeve 3. Thus by properly spacing the outlet ports 26 and 21, the pressure necessary to move the valve stem 6 and'its control elements 18 can be controlled over a wide range regardless of the tension of the spring 9; By this construction the spring tension of the valve can be regulated to govern the reopening of the valve but the closing pressure may be controlled by the location size and number of the ports 26 and 21.

It will be noted that valve element I is formed with .an offset IA. This reduced .ofiset IA afiordsthe contact means or seating surface to engage the valve seat 4 on the sleeve 3. The larger part of valve I afiords means to utilize the sweep effect of the gas ntering compartment 25 irom her of ports are at 26 for the reason that if a large part of the gas passing through the sleeve 3 escapes out of the ports 26, it will require a higher pressure to force the element 1 to its extreme travel and thus close the valve to passage of gas. Therefore, with a spring of constant tension, the closing pressure of the valve can be raised or lowered without adjustment of the spring.

After gas has entered through air nipple 22 into the interior of the valve housing 2 into compartment IS in its travel through the sleeve-3 to compartment 25 the velocity of such gas passage exerts a pull on the stem 6 and valve element I tending to force the stem 6 in a direction of the outlet ports 26 and 21. Regardless of where the ports 2621 are located with relation to the sleeve 3 at varying differential or pressure the element 8 will be forced onto seat 5 thus closing off any passage of gas through the valve. After having become closed due to velocity of the gas through the valve, any internal pressure in the tubing having communication with the interior of the valve through ports 26'21 will exert a pressure through the sleeve 3 on the under side of valve element 8 and on the end of stem 6 in the zone of the spring retainer, and thereby cause the valve stem 6 to move in the opposite direction, thus disengaging element 8 from seat 5 and gas pressure will again passthrough the valve exerting a pressure to again close the valve. The pressure necessary to reopen the valve by internal tubing pressure will be that pressure plus the tension of the spring 9 that is necessary to overcome the locking effect of pressure gas constantly exerted on the end of the stem 6 exposed to said pressure gas in the zone of plug l3 and the overlap of element 8 on its seat 5. Since it is readily seen that in normal position the spring 9 maintains valve element 1 in contact with the seat 4 of the sleeve, it will be understood that whenever the internal pressure of the tubing rises to a degree where it overcomes the efiect of the gas on the stem as above, unless pressure gas is available at sufficient pressure to again pass through the valve and thereby exert a pressure to close the valve again, the valve element 1 will contact seat 4 and remain so until pressure gas again prevails that will overcome the tension of the spring plus the internal pressure of the tubing and then gas will resume passage thru the valve I. By setting a given tension on the spring to cause the valve to reopen with a predetermined internal pressure of the tubing, it is possible by proper location of the ports 26-21 to close the valve with a difl 'erential pressure only slightly affected by the tension of the gitudinal slot 31 extending through the partition 32 between the eduotion passage 39 and said chamber 23 extending longitudinally the entire length of the chamber 23. The valve l is introduced into this chamber through the interior of coupling A and secured therein by air nipple 22 and hanger pin 33, whereby the valve I is mounted within the chamber as shown in Figure 2.

The coupling 5A is provided with internal threads 34 which threads engage external threads 35 on the ends of adjoining sections of an eduction tube 28 which extends down into the casing 29 of the wall, there being a casing head on the upper end of said casing 35 above the ground, through which head the upper end of the eduction tube 23 extends and in which said tube is suspended. A plurality of couplings 5A containing the valve I connect sections of the eduction tube 28 at spaced intervals in the well and the eduction tube may extend through a packer 37 down in the well casing 29L Into the casing 36 is secured a pipe 38 for supplying fluid such as air or gas under pressure to the casing 29. On the upper end of the eduction tube 28 is secured a T-joint 39 or other suitable arrangement of piping, to which is connected pipes 40 and M, the pipe 50 being a delivery pipe for delivering liquid lifted through the eduction tube to a suitable container for storage. The pipe 4| is also connected to a valve 42 and said valve is also connected to a T-connection 43 in the supply line 38 serving as an equalizing line between the tube 28 and the casing 29 of the well. The operation,

uses and advantages of the invention are as follows:

Ordinarily in oil wells, the liquid therein, whether oil, water or a mixture of both, the level to which the fluid rises varies over a wide range in difierent fields and localities, regardless of the depth of the well. Oil, gas and water accumulated in the formations of the earth, are therefore known to be under many different pressure conditions, and therefore, the variation in the depth of the fluid encountered in each well, or stated reversely, upon this formation pressure depends the height in the well bore or casing the fluid rises. In the application of valves such as corn templated herein to oil wells, the well is assumed to be anon-flowing type well, so that the fluid level in such well, is at static condition and at constant level in the well depending upon the formation pressure as above.

Therefore, in the application of the valves, the

fluid level is determined by measuring line or other facility, and the tubing installed in the well; as the tubing is installed, a packer may be corn nected therewith in such manner as to create a reservoir pressure chamber between the well tubing and the casing, and for the additional purpose of maintaining the formation free from the effect of direct contact with the gas applied to said reservoir. In wells, where high formation pressure exists or usually where water drive is present, no packer is required, however, with or without a packer, as the tubing is installed in a well, valves are attached to said tubing at intervals in the tubing sections, so that the top valve in the tubing string will be located at or near the static fluid level when the tubing is finally lowered into the well to the desired depth. Likewise, the balance of the valves located below the top one will be spaced apart in proportion to the weight of the fluid, the available pressure in the casing to operate the well with, and the lowest valve will be at a distance up from the bottom-of the well thought desirable to accomplish the. desired effect of either flowing around the bottom of the tubing or operating from adistance up from the bottom that precludes the possibility of flowing around the bottom. In the case of a packer, the-lower valve is contemplated to be located immediately above the packer so that fluid can be drawn or produced from as near the bottom of the well as possible, this assisting the packer in reducing the static pressure exerted back against the formationby its height.

In wells equipped so that circulation around the bottom of the tubing cannot take place as illusv trated above herewith wherein the bottom valve is located an appreciable distance up from the bottom, or where a packer is employed, it will be seen, that as the static fluid level is lowered by the action of the valves, the lowest depth at which flow can take place with the valves in either instance is reached, and the flow or ejection rate of the fluid up the tubing will have exceeded the input rate of the well, there occurs a rest period during which the bottom valve will be closed by virtue of exhausting the fluid as above, and there fore after this condition obtains, the fluid input of the well continues, and fluid rises above thelower valve. The valve therefore must be of the re-opening type, otherwise the fluid would rise to its former static height, and the well would not flow again until manually the well was started again, probably by equalizing the pressure in the tubing and easing thereby opening the valves. However, to promote trouble free and automatic operation, the valves must be automatically controlled by the rising fluid after any period of exhaustion as above, and reopen to admit gas to re-establish flow. This operation may be of heavy or varying rate of intensity, depending upon the desire of the operator. The valves may be so adjusted in their opening differential pressure, so that the flow will be of less intensity and thereby extend the flowing period of each cycle so that they nearly overlap, or be regulated so that each cycle of re-opening is violent and the flow takes place in an instant and results in intermittent slug type flow, A valve to accomplish all these functions is of course an advantage.

In this discussion of opening differentials, it is to be understood that this dilference means the weight of the load of well fluid under the existing casing pressure so that only sufficient weight is permitted to accumulate in the well before the valve opens up; otherwise, if the weight is allowed to build up to nearly approach the existing gas pressure when the valve opens, no flow will take place for the reason that at such low differential the volume of gas passing through the port of the valve will not sustain flow. 7

Besides the opening of the valve the closing dif: ferential pressure is governed by the same considerations. That is a closing pressure differential must be employed, so that as unloading takes place, from one valve to another, the volume of gas passing through any valve is governed by the diiferential pressure employed, therefore; aswill be seen if a mistake in judgment exists in selection of closing pressure a valve may become closed before unloading all the fluid thereabove 'inthe tubing, and if it were not for the re-opening ability of the valve, the well would not again flow,unless manually operated. Therefore, spacing of the valves is governed by these dilferentialsi in order to reduce the number of valves employed, as high an opening pressure or closing pressure is used so as to reopen wlththe greatest weightposs'ib-le. In operation, however, limitations of these differentials is governed by the available gas supply, and although sufficient volume may be present, pressure may be less than required to employ far spacings. To adjust for these field conditions, which are beyond the control of the operator different opening pressure and closing differentials must be employed. Since it is impossible to create any differential of magnitude in very deep wells with low pressure, heretofore, with other valves, it has been necessary to use valve only down to a limited depth from which the fluid could be produced for the reason that as depth in a well is reached, an increase flowing'pressure is required. Since this flowing pressure will ultimately be all that exists, there is no surplus to create a differential to close the valve. For this reason the present valveincorporates a feature that is new and novel.

In such a condition as above, study of the valve indicates that a certain differential is required at the start to open the valve for gas passage as the valve is in seated position upwardly. This differential'is adjusted so that, considering port size, and capacity at this differential opening pressure, the fluid in the well must be lifted. Opening o-p-' eration of the valve, the depth of the well finally having been reached where the closing pressure dilferential in the lower position or second closing position, is impossible to create, the valvereturns to the first closing, or in upper position, and remains so until the casing pressure is raised, which will ordinarily prevail, particularly since consumption has ceased, and therefore, pressure must rise to that existing at the beginning.

Assume a valve set for a first opening differential of 100 pounds. In which case the port size employed will permit a volume of gas to pass through the valve that will establish sufficient flowing speed to blow the fluid from the well. After the fluid load has been expelled, the pressure in the tubing has declined to only the friction flow of the gas passing through the valve. Therefore, additional differential is available to force the valve into its lower or second closing position. Assume this second differential pressure to force the valve through its length of travel to be 125 pounds. Further assuming that this is the bottom valve, that the valve remains shut until the fluid in the well rises above the valve again. If the opening pressure of the valve be now set for 110 pounds as soon as the oil rises in the tubing above the valve within 110 pounds of the casing pressure (110) differential. the valve opens and gas at this differential passes through the vave. Since at this pressure an abundance of gas is passing, a great pressure is built up in the tubing consisting of the pressure of the fluid; the pressure caused by the flow, or friction, and under these conditions, any valves thereabove are likely to be forced open, since the internal pressure will ordinarily lie within their reopening differential. With ordinary valves, if this condition occurred, all valves in the spring would open and such a flow of gas thus admitted to the tubing would create a friction flow that would eliminate the closing of any valves and the well would have to be shut down. With the valve here disclosed, whenever an excessive pressure occurs by the re-opening of any valve, the valves thereabove as well as the valve in operation is forced through its travel in reverse to the first position of closing, until the differential reaches the pressure at which it will again open (100),

so that a safety factor is thus utilized, compelling 75 a constant and even flow; employing any excessive pressure to close all potential fouled valves and compelling one or more to introduce at a steady rate until the load which opens any valve has been removed from the well, completing the cycle.

Also, many times it is necessary to set a high differential opening valve, in second position, in order to lift the fluid from a well. However, if the differential closing pressure cannot be reached due to low line pressure it becomes necessary to fix the re-opening pressure to flow the well as above, but the closing must be reduced. In this structure by employing one standard spring to govern the opening and re-opening pressure, but employing outlet ports at strategic positions with relation to the valve element, any closing pressure desired can be obtained without adjusting or disturbing the spring. By permitting the gas to escape immediately adjacent the seat in the valve on the outlet side, it will be observed there is not suificient volume to force the valve to its lower position, and therefore, a very high closing differential results. On the other hand, if the outlet ports are moved back so that most of the gas is compelled to escape near the bottom of the valve travel, a lower pressure will force the valve to closed position in its extreme lower position.

In the valve casing 5A, a novel tubing coupling is employed for the valve holding mechanism, and consists of an elongated casting or nipple with a hollow side portion having a semi-rounded covering inside of which the valve is contained at one side of the central bore of. the casting. The rounded raised portion may either be an integral part of the casting or welded on the side of a nipple. However, in the casting, a slot running longitudinally with the bore, comprising a full opening whereby the valve maybe inserted at either end of the casting and set into the offset rounded portion where it may be attached to either side, or the top of the rounded portion, thereby securing the valve so as to have control over a port of the same in said rounded offset portion of the casting. The valve being secured to this port by a lock nut screwed onto the'air nipple of the valve into a counterbore of the casting so as to remove said nut from any possibility of fouling and become knocked off in lowering the tubing into the well. The same method of securing the hanger pin 29 is employed. With this type casting, loose covers are avoided; no bolts being employed, and therefore, with the valve mounted from internally the casting, easy removal of the valve results when necessary to repair, with no special tools required. The casting of one piece construction, and method of inserting the valve and removing same is a novel improvement over conventional castings of this type.

Having described the invention and clearly pointed out its novelty and advantages and means of construction, we claim:

1. A gas-lift valve comprising a tubular housing, a sleeve therein intermediate its ends, a valve stem slidably operable through said sleeve, valve elements on said valve stem spaced apart one on. either side of said sleeve, seating surfaces on said valve elements'for contacting said sleeve, a gas inlet into the valve housing at one side of said sleeve, clearance around said valve stem within said sleeve, small apertures through the walls of the said valve housing forming gas outlets, at the other side of said sleeve, a spring holding said valve stem in position whereby one of said elements is in contact with the said sleeve, and

spring retainer head attached internally at one end of the said housing and a valve guide head forming a plug at the opposite end of the said housing, said plug counterbored internally to cooperate with one end of said valve stem as a guide.

2. A gas controlling valve comprising a tubular housing, a sleeve mounted therein intermediate the ends thereof, a valve stem slidably operable through said sleeve, valve elements on said valve stem spaced apart one on either side of said sleeve, seating surfaces on said valve elements for contacting said sleeve alternately, when said stem is moved in either direction a predetermined distance, an element of larger diameter than the above said valve elements mounted on said stem adjacent one of said first elements forming a piston, a gas inlet port into the said valve housing at one side of said sleeve, clearance around said valve stem in said sleeve, a series of apertures through the wall of said housing forming gas outlets at the opposite side of said sleeve from the said inlet port, whereby pressure required to move said valve stem in the direction of the said outlet ports is controlled by their size and spaced relationship to the outlet side of said sleeve, tension means Within said housing in association with said stem maintaining said stem and a valve element in contact with the said sleeve and resisting movement of said stem in the direction of said outlet apertures, an adjustable spring retainer head forming a closure for said housing at one end thereof, and plug means at the opposite end of said housing forming a valve stem guide. 

